Fraunhofer-Institut für Produktionsanlagen und Konstruktionstechnik IPK

Filters

2
2 2
Reset filters

Settings
Now showing 1 - 2 of 2
  • Publication
    Micro-cutting of a MMC-composite for enhanced injection moulds
    ( 2019)
    Uhlmann, E.
    ;
    Polte, M.
    ;
    Hein, C.
    ;
    Polte, J.
    ;
    Jahnke, C.
    Tools for micro-injection moulding are currently made of hardened steel. These tools are exposed to high local loads, which significantly reduce the injection moulding tool life time tT. Furthermore, the occurring wear of the milling tool during machining of hardened steel leads to reduced surface roughness Ra and geometrical accuracy GF. Copper and aluminium alloys as mould materials provide an alternative to hardened steel with advantages regarding material removal rate QW and wear of the milling tool, but with a significantly reduced life time of the injection moulding tool tT. Until now, the combination of a good machinability and high wear resistance cannot be achieved. The approach, presented in this paper consists of an easy to machine material and the development of a wear resistant metal-matrix-composite (MMC) material layer with a hardness of up to 3,000 HV. Therefore, the pre-machined test specimens made of aluminium-bronze are coated by laser dispersing with wolfram-carbide-particles W2C-WC. Furthermore, for the finishing machining of the coated moulds, a cutting technology for the machining of W2C-WC-particles was developed. The verification of the developed technology was performed with an injection moulding process based on carbon-fibre reinforced thermoplastic material. By means of documented machining efforts, the quality indicators geometrical accuracy GF and surface roughness Ra as well as occurring tool wear, the feasibility of the developed technology was demonstrated.
  • Publication
    Die-sinking EDM of a SiC-boride-composite
    ( 2019)
    Uhlmann, E.
    ;
    Polte, J.
    ;
    Jahnke, C.
    ;
    Wolf, C.-S.
    ;
    Degenhardt, U.
    Silicon carbide-based composites are highly demanded for industrial applications, like heat exchangers in corrosive environments. In consequence of the mechanical properties like high hardness H and brittleness, cutting processes are still challenging. An opportunity for processing difficult-to-cut materials with sufficient electrical conductivity s is electrical discharge machining (EDM). In order to develop suitable machining technologies, known parameters for common material combinations can serve as a starting point. Hence, standard technologies from the database of a commercial die-sinking EDM machine tool were applied for machining a silicon carbide-boride-composite. The material removal rate QW and the arithmetical mean deviation Ra for finishing and roughing operations are observed. The formation of cracks and the extend of the typical deposition layer formed at the surface of the workpiece is analysed through scanning electron microscopy. While the material removal rate QW is increasing with higher discharge energies W in this investigation, the arithmetical mean deviation Ra is not dependent on this property. Furthermore, spalling is identified as main material removal mechanism occurring in this process. Overall, the machinability of silicon carbide-boride composites with EDM, applying commercial available parameter technologies, is successfully demonstrated.